Tooth decay sits on a spectrum, and so does the treatment for it. The earlier it’s caught, the smaller the intervention, and that’s still the single biggest factor in keeping things simple.
Patients often arrive thinking decay is a binary: either there’s a hole, or there isn’t. Restorative dental treatment covers a far wider range than that, and the choice between a small filling and a crown depends on factors most people never get told about. The honest summary is that we’d rather see you for a small problem now than a large one in twelve months.
How decay actually progresses
Decay starts as a chemical attack on enamel. Acid produced by oral bacteria dissolves the mineral content of the tooth surface. At this earliest stage, before any cavity has formed, the damage is reversible with fluoride and improved plaque control. We see this all the time on the inside surfaces of upper front teeth, often in patients who’ve been drinking too much fizzy water or carbonated drinks without realising the cumulative effect.
If the demineralisation continues, enamel breaks down and a cavity forms. Once the surface is broken, the tooth can’t repair itself. Decay then spreads through dentine (the softer layer beneath enamel) and, eventually, into the pulp where the nerve and blood supply sit. Once the pulp is infected, the tooth has crossed from “needs filling” to “needs root canal”.
This progression isn’t linear. Some cavities sit at a slow pace for years. Others race through dentine in months. The variability depends on diet, saliva flow, plaque control, the specific tooth involved, and a degree of genetic luck.
The treatment ladder, from least to most invasive
The principle in modern dentistry is to do the minimum needed to stop the disease and restore function. Bigger isn’t better. A heavily prepared tooth is a weakened tooth, and we’d rather repeat a small repair in ten years than over-prepare a tooth now and end up with a crown by 50.
| Stage of decay | Typical treatment | Time in chair | NHS band (England) |
|---|---|---|---|
| Early demineralisation | Fluoride application, dietary advice, monitoring | 10 to 20 minutes | Band 1 (£27.90) |
| Small enamel cavity | Composite filling | 30 to 45 minutes | Band 2 (£76.60) |
| Moderate cavity into dentine | Larger composite or inlay | 45 to 75 minutes | Band 2 or Band 3 (£332.10) |
| Deep cavity, pulp threatened | Indirect pulp cap, then composite or onlay | 60 to 90 minutes | Band 2 |
| Pulp involvement / abscess | Root canal then crown | 2 to 3 visits, 60 to 90 mins each | Band 2 (RCT) plus Band 3 (crown) |
| Tooth broken below the gum | Crown lengthening or extraction with replacement | Multiple visits | Variable |
The leap that surprises patients is the one between a large filling and a crown. The conventional rule of thumb is that if more than half of the tooth’s structure is gone (or about to be removed during cavity preparation), a crown gives a more reliable long-term outcome than a heroic filling.
Why composite has largely replaced amalgam
For decades, amalgam (“silver” fillings) was the standard restorative material for back teeth. It’s durable, cheap, and forgiving of moisture. It’s also visually obvious and, increasingly, falling out of favour for environmental and cosmetic reasons. The Minamata Convention has been pushing global reduction of mercury-containing dental materials for years, and most NHS practices in England now place composite fillings as the default for many cavities, particularly in patients under 15, pregnant women, and breastfeeding mothers.
Composite is bonded to the tooth, which means less healthy structure has to be removed during preparation. It looks like enamel. It’s repairable. The downside, if there is one, is that it’s more technique-sensitive: the bond fails if the tooth isn’t kept dry during placement, and that adds a few minutes to each filling.
In our experience, modern composites perform comparably to amalgam in most situations. The exceptions are very large cavities in heavy grinders, where neither material is ideal and we usually recommend an onlay or crown instead.
The role of crowns and onlays
When decay or previous restorations have left a tooth structurally compromised, a crown or onlay redistributes the bite forces over a wider area and reduces the risk of catastrophic fracture. Crowns cover the whole tooth above the gum line. Onlays cover only the chewing surface and are more conservative.
Online, you’ll see articles claiming crowns are over-prescribed and that all but the most damaged teeth should be left alone with composite. The reality is more layered than that. A composite repair on a heavily filled molar in a grinder will often fail within a few years. The same molar with a well-fitted ceramic onlay or crown will last fifteen to twenty. Trying to save the tooth with composite at that stage is sometimes the right call. Often, it isn’t.
Actually, more accurately: the choice depends on the bite, the patient’s grinding habits, and how the tooth has held up to previous restorations. A blanket rule misses too many of the relevant factors.
What patients usually don’t know
Most patients we see for repeat decay aren’t dealing with a brushing problem. They’re dealing with a diet problem, a saliva problem, or both. The pattern is consistent: a patient with three or four new cavities in a year almost always has a sugar exposure pattern (snacking through the day, sweet drinks, late-night sweet teas) that’s keeping the mouth acidic for hours longer than the tooth can cope with.
Frequency matters more than quantity. Six biscuits eaten with a single cup of tea is far less damaging than six biscuits eaten one per hour through the afternoon. The former gives the saliva time to neutralise the acid. The latter doesn’t.
That’s a hard pattern to change. But it’s the most useful thing we can flag.
Prevention, briefly
You can read more about how decay forms and how to reduce your risk on the NHS tooth decay page. The short version: brush twice daily with fluoride toothpaste (1450 ppm minimum for adults), don’t rinse afterwards, clean between the teeth daily with floss or interdental brushes, and limit sugar to mealtimes rather than spreading it through the day.
For NHS patients in England, examinations sit at Band 1 (£27.90) and most fillings or extractions sit at Band 2 (£76.60). Crowns, bridges, and dentures sit at Band 3 (£332.10). Children under 18, and under 19 in qualifying full-time education, receive NHS treatment free.
When the decay is hidden
One last thing worth flagging. Decay between teeth often doesn’t show on a normal visual examination. We rely on bitewing X-rays, taken every one to two years, to catch it early. Patients sometimes ask if they can skip these to reduce radiation exposure; the dose is extremely low and the diagnostic value is high. We’ve found cavities that were no bigger than a pinhead on X-ray, treated them with a tiny composite, and avoided what would have been a crown two years later.
After a filling or crown is placed, the bite needs checking once or twice in the following weeks. Composite settles slightly, the surrounding teeth shift fractionally, and what felt right on the day occasionally feels high a week later. A two-minute adjustment fixes it. Left alone, a high contact can crack the new restoration or sensitise the tooth.
Patients often don’t come back for these adjustments because they assume any minor discomfort will settle on its own. Sometimes it does. Often, a small bite tweak resolves it within seconds. We’d rather see you for a quick adjustment than have you put up with a problem that’s easy to fix.
If you’d like a thorough decay assessment or you’ve got a tooth that’s been niggling for a while, our team at Westcliff Dental Practice can see you for a check-up and explain exactly what stage you’re at and what (if anything) needs doing. Give us a call on 01702 344 500 and we’ll find you a slot that works.
